Sensor bearing unit and associated manufacturing method

ABSTRACT

A sensor bearing unit includes a bearing having a first ring and a second ring, and an impulse ring provided with a target holder, with a target mounted on the target holder, and with a sleeve secured to the first ring, the target holder being axially mounted between a lateral face of the first ring and the sleeve. The first ring having at least one anti-rotation feature cooperating with at least one complementary anti-rotation feature formed on the impulse ring so as to prevent angular movement of the impulse ring relative to the first ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application no.102020125222.6, filed Sep. 28, 2020, the contents of which is fullyincorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a sensor bearing unit comprising abearing and an impulse ring.

BACKGROUND OF THE INVENTION

Today, sensor bearing units are commonly used in a wide range oftechnical fields, for example in automotive industry and aeronautics.These units provide high quality signals and transmissions, whileallowing integration in simpler and more compact apparatus.

Such a sensor bearing unit generally comprises a bearing, an impulsering, and detection means facing the impulse ring. For example, theimpulse ring is provided with a target holder and with a magnetizedtarget fixed to the target holder beyond the outer ring of the bearing.

The magnetic target includes alternating North and South poles, whosenumber depends on bearing size, detection precision and particularapplication. The detection means may be fixed to the outer ring of thebearing or to a fixed casing. The magnetic target is attached to anouter tubular portion of the target holder.

In a first type of impulse ring, the target holder is also provided withan inner tubular portion secured into an annular groove made in the boreof the inner ring in order to prevent the rotation of the impulse ringrelative to the inner ring. To this end, the target holder is radiallycrimped into the annular groove of the inner ring.

In a second type of impulse ring, the impulse ring is also provided witha fixing sleeve supporting the target holder and secured to the innerring. The sleeve comprises an annular axial portion and a radial collarextending radially outwards the axial portion, the target holder beingaxially mounted between the inner ring of the bearing and the radialcollar of the sleeve. For more details, it is possible for example torefer to the U.S. Pat. No. 10,132,359.

Similarly, to the first type of impulse ring, the axial portion of thesleeve is secured into the annular groove of the inner ring in order toprevent the rotation of the impulse ring relative to the inner ring.

It is essential that the impulse ring is fixedly connected in rotationwith the bearing ring to which it is attached.

In some cases, due to high speeds, thermal dilatation or high mechanicalloads, there is a significant risk that the angular mechanic connectionbetween the impulse ring and the bearing ring holding it becomespartially or totally loose, permanently, or randomly. Should such afailure occur, the signal measured by the detection means would notcorrespond to the real position or speed or acceleration of one of thetwo bearing rings with respect to the other.

One aim of the present invention is to provide a sensor bearing unitwith improved angular connection between the impulse ring and theassociated ring.

SUMMARY OF THE INVENTION

The invention relates to a sensor bearing unit comprising a bearingprovided with a first ring and a second ring centered on an axis, and animpulse ring provided with a target holder, with a target mounted on thetarget holder, and with a sleeve secured to the first ring of thebearing.

The target holder is axially mounted between a lateral face of the firstring of the bearing and the sleeve.

According to a first general feature, the first ring of the bearingcomprises anti-rotation means cooperating with complementaryanti-rotation means of the impulse ring so as to prevent angularmovement of the impulse ring relative to the first ring.

According to a second general feature, the anti-rotation means of thefirst ring of the bearing are formed on the lateral face of the firstring, and/or extend from the lateral face.

According to a third general feature, the complementary anti-rotationmeans of the impulse ring extend into the anti-rotation means of thefirst ring. Alternatively, the anti-rotation means of the first ring mayextend into the complementary anti-rotation means of the impulse ring.

Preferably, both the anti-rotation means of the first ring of thebearing and the complementary anti-rotation means of the impulse ringextend in the circumferential direction over a limited angular sector.In other words, the anti-rotation means of the first ring and theimpulse ring are not annular. Accordingly, any relative rotation betweenthe impulse ring and the first ring is prevented by abutment incircumferential direction.

The sleeve of the impulse ring may comprise a mounting portion securedto the first ring of the bearing, and a collar extending radiallyoutwards the mounting portion. The target holder is axially mountedbetween the lateral face of the first ring of the bearing and the collarof the sleeve.

In one embodiment, the mounting portion of the sleeve extends purelyaxially.

A radial gap may subsist between the bore of the target holder of theimpulse ring and the sleeve.

According to a first design, the anti-rotation means of the first ringof the bearing comprise at least one anti-rotation recessed portion.

In one embodiment, the anti-rotation recessed portion of the first ringof the bearing comprises at least one slot formed on the lateral face ofthe first ring, the target holder of the impulse ring comprising atleast one lug extending into the slot, the lug forming at least partlythe complementary anti-rotation means of the impulse ring. The slot andlug may extend axially. Alternatively, the slot and lug may extendobliquely.

In another embodiment, the anti-rotation recessed portion of the firstring of the bearing comprises at least one axial groove extending fromthe lateral face of the first ring axially along a cylindrical surfaceof the first ring, the sleeve comprising at least one boss extendinginto the axial groove and being of complementary shape, the boss formingat least partly the complementary anti-rotation means of the impulsering. The anti-rotation recessed portion of the first ring may comprisea plurality of axial grooves spaced apart in the circumferentialdirection, the sleeve comprising a plurality of bosses each extendinginto one of the axial grooves.

Alternatively, or in combination, the anti-rotation recessed portion ofthe first ring of the bearing may comprise at least one radial grooveformed on the lateral face of the first ring, the target holdercomprising at least one boss extending into the radial groove and beingof complementary shape, the boss forming at least partly thecomplementary anti-rotation means of the impulse ring. The anti-rotationrecessed portion of the first ring may comprise a plurality of radialgrooves spaced apart in the circumferential direction, the sleevecomprising a plurality of bosses each extending into one of the radialgrooves.

In another embodiment, the anti-rotation recessed portion of the firstring of the bearing may comprise an eccentric groove formed on thelateral face of the first ring, the target holder comprising aneccentric rib extending into the eccentric groove and being ofcomplementary shape, the eccentric rib forming at least partly thecomplementary anti-rotation means of the impulse ring.

According to a second design, the anti-rotation means of the impulsering comprise at least one anti-rotation recessed portion.

In one embodiment, the anti-rotation recessed portion of the impulsering comprises at least one slot formed on the target holder, thelateral face of the first ring of the bearing comprising at least onelug extending from the lateral face into the slot. The slot and lug mayextend axially. Alternatively, the slot and lug may extend obliquely.

In another embodiment, the anti-rotation recessed portion of the impulsering comprises at least one axial groove extending along a cylindricalsurface of the sleeve, the first ring of the bearing comprising at leastone boss extending into the axial groove and being of complementaryshape, the boss extending from the lateral face of the first ring.

Alternatively, or in combination, the anti-rotation recessed portion ofthe impulse ring comprise at least one radial groove formed on thetarget holder, the lateral face of the first ring of the bearingcomprising at least one boss extending into the radial groove and beingof complementary shape, the boss extending from the lateral face of thefirst ring.

In another embodiment, the anti-rotation recessed portion of the impulsering may comprise an eccentric groove formed on target holder, thelateral face of the first ring of the bearing comprising an eccentricrib extending into the eccentric groove and being of complementaryshape, the eccentric rib extending from the lateral face of the firstring.

The invention also relates to a sensor bearing unit comprising a bearingprovided with a first ring and a second ring centered on an axis, and animpulse ring provided with a target holder, with a target mounted on thetarget holder, and with a sleeve secured to the first ring of thebearing.

The target holder is axially mounted between a lateral face of the firstring of the bearing and the sleeve.

According to a first general feature, the first ring of the bearingcomprises anti-rotation means cooperating with complementaryanti-rotation means of the impulse ring so as to prevent angularmovement of the impulse ring relative to the first ring.

According to a second general feature, the anti-rotation means of thefirst ring of the bearing and the anti-rotation means of the impulsering extend in the circumferential direction over a limited angularsector.

According to a third general feature, the anti-rotation means of theimpulse ring extend into the anti-rotation means of the first ring.Alternatively, the anti-rotation means of the first ring may extend intothe anti-rotation means of the impulse ring.

The invention further relates to a method for manufacturing a sensorbearing unit as previously defined, wherein the sleeve is secured to thefirst ring only by axial press-fitting.

In one embodiment, the anti-rotation means of the impulse ring, or theanti-rotation means of the first ring, may be formed during the step ofaxial press-fitting.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention and its advantages will be better understood bystudying the detailed description of specific embodiments given by wayof a non-limiting examples and illustrated by the appended drawings onwhich:

FIG. 1 is an axial section view of a sensor bearing unit according to afirst example of the invention,

FIG. 2 is a detail view of FIG. 1,

FIG. 3 is a perspective view of a target holder of an impulse ring ofthe sensor bearing unit of FIG. 1,

FIG. 4 is a detail view of a bearing of the sensor bearing unit of FIG.1,

FIGS. 5 and 6 are detail views of a sensor bearing unit according to asecond example of the invention,

FIGS. 7 to 9 are detail views of a sensor bearing unit according to athird example of the invention,

FIGS. 10 to 12 are detail views of a sensor bearing unit according to afourth example of the invention,

FIGS. 13 to 15 are detail views of a sensor bearing unit according to afifth example of the invention, and

FIG. 16 is a detail view of a sensor bearing unit according to a sixthexample of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The sensor bearing unit 10 represented on FIG. 1 is adapted to equip anapparatus such as a motor, a brake system, a suspension system or anyrotating machine, in particular for an automotive vehicle.

The sensor bearing unit 10 comprises a bearing 12 and an impulse ring 14mounted on the bearing.

The bearing 12 comprises a first ring 16 and a second ring 18. In theillustrated example, the first ring 16 is the inner ring whereas thesecond ring 18 is the outer ring. The inner and outer rings 16, 18 areconcentric and extend axially along the bearing rotation axis X-X′ whichruns in an axial direction. The inner and outer rings 16, 18 are made ofsteel.

In the illustrated example, the bearing 12 also comprises a row ofrolling elements 20, which are provided here in the form of balls,interposed between raceways (not referenced) formed on the inner andouter rings 16, 18. The rolling bearing 10 also comprises a cage 22 formaintaining the regular circumferential spacing of the rolling elements20.

The inner ring 16 of the bearing is intended to be mounted on a shaft ofthe apparatus for tracking the rotation of the shaft. The inner ring 16is intended to rotate while the outer ring 18 is intended to be fixed.The outer ring 18 can be mounted in a fixed support member or housing,belonging to the apparatus.

The inner ring 16 comprises a cylindrical inner surface or bore 16 a andan outer cylindrical surface 16 b which is radially opposite to the bore16 a. A toroidal circular raceway for the rolling elements 20 is formedfrom the outer cylindrical surface 16 b, the raceway being directedradially outwards.

The inner ring 16 also comprises two opposite radial lateral faces 16 c,16 d which axially delimit the bore 16 a and the outer surface 16 b ofthe ring.

The inner ring 16 further comprises a cylindrical groove 16 e made inthe bore 16 a. The groove 16 e is centered on the axis X-X′. Diameter ofbore 16 a is smaller than diameter of groove 16 e. The groove 16 e openson the radial lateral face 16 d.

The impulse ring 14 is mounted on the inner ring 16. The impulse ring 14comprises an annular target holder 30, a target 32 mounted on the targetholder, and a fixing sleeve 34 secured to the inner ring 16.

The target holder 30 is axially secured to the inner ring 16 of thebearing by means of the sleeve 34. The target holder 30 is axiallymounted between the lateral face 16 d of the inner ring of the bearingand the sleeve 34. The target holder 30 is mounted radially around thesleeve 34. The target holder 30 is axially interposed and clampedbetween the lateral face 16 d of the inner ring and the sleeve 34. Thetarget holder 30 is in axial contact against the lateral face 16 d ofthe inner ring on one side and in axial contact with the sleeve 34 onthe other side.

The target holder 30 comprises an annular radial portion 30 a definingthe bore of the target holder, and an outer annular axial portion 30 bradially surrounding the bearing 12. The outer axial portion 30 b islocated radially above the outer ring 18 of the bearing. The outer axialportion 30 b extends radially a large-diameter edge of the radialportion 30 a.

The radial portion 30 a of the target is axially interposed and clampedbetween the lateral face 16 d of the inner ring of the bearing and thesleeve 34. In the illustrated example, the radial portion 30 a of thetarget holder is provided with frustoconical parts inclined with respectto the axis X-X′ towards the opposite direction of the bearing 12.Frustoconical parts prevent any interference between the target holder30 and the outer ring 18 of the bearing.

As will be described later, the target holder 30 also comprises lugs 36in order to prevent angular movement relative to the inner ring 16 ofthe bearing.

In the disclosed example, the target holder 30 is made in one part. Thetarget holder 30 may be made of metal or plastic, formed by stamping orby any other suitable process.

The sleeve 34 is axially secured to the inner ring 16. The sleeve 34 ismounted into the bore 16 a of the inner ring of the bearing. The sleeve34 is secured into the bore 16 a. More precisely, the sleeve 34 ismounted and secured into the groove 16 e of the bore. For example, thesleeve 34 may be secured into the bore 16 a of the inner ring 16 e, byaxial press-fitting.

As previously mentioned, the sleeve 34 is axially secured to the innerring 16. The sleeve 34 may also be angularly secured to the inner ring16 to fasten in rotation the sleeve and inner ring 16. In this case, thesleeve 34 may be secured into the bore 16 a by snapping, by gluing, bywelding, by radial crimping or any other appropriate means.

The sleeve 34 comprises an annular axial portion 34 a defining the boreof the sleeve, and an outer radial portion or collar 34 b extendingradially from the axial portion 34 a. The collar 34 b extends radiallyoutwards from the axial portion 34 a. The collar 34 b extends an axialend of the axial portion 34 a.

The target holder 30 is mounted radially around the axial portion 34 aof the sleeve. The radial portion 30 a of the target holder is mountedradially around the axial portion 34 a. An annular radial gap (notreferenced) subsists between the bore of the target holder 30 and theaxial portion 34 a of the sleeve. The axial portion 34 a of the sleeveis secured to the inner ring 16 of the bearing. The axial portion 34 ais mounted and secured into the bore 16 a of the inner ring of thebearing. More precisely, the axial portion 34 a of the sleeve is mountedand secured into the groove 16 e of the bore.

The target holder 30 is axially interposed and clamped between thelateral face 16 d of the inner ring and the radial collar 34 b of thesleeve 34. The radial collar 34 b axially abuts against the radialportion 30 a of the target holder.

In the disclosed example, the sleeve 34 is made in one part. The sleeve34 may be made of metal or plastic, formed by stamping or by any othersuitable process.

The target 32 is mounted on the outer axial portion 30 b of the targetholder. In the disclosed example, the target 32 is mounted into the boreof the outer axial portion 30 b. Alternatively, the target 32 may bemounted on the outer surface of the outer axial portion 30 b.

In an embodiment, the target 32 includes magnetic North and Southalternated poles. The target 32 is multi-polarly magnetized in thecircumferentially direction. The target 32 may be a plastic molded part.The target 32 may be overmolded onto the target holder 30.

Alternatively, the target 32 may be separately formed and secured ontothe target holder 30 by any appropriate means, for example by bonding orby press-fitting. The target 32 may be formed of a rubber material withmagnetic powder, or of a magnetic alloy or of a plasto-ferrite or of anelasto-ferrite.

Detection means (not shown) are associated with the target 32 fortracking the rotation of the impulse ring 14 and the inner ring 16around the axis X-X′. The detection means are disposed to radially facethe inner surface of the target 32. For example, the detection means mayinclude Hall-effect sensors. The target 32 is a radial target.Alternatively, the target may be an axial target.

As an alternative, the target 32 and the detection means may use anyother suitable technology instead of magnetic technology. For example,induction technology or optic technology may be implemented.

As previously indicated, the target holder 30 comprises lugs 36 in orderto form anti-rotations means. The lugs 36 extend from the radial portion30 a of the target holder towards the inner ring 16 of the bearing. Thelugs 36 extend axially towards the inner ring 16.

As shown more clearly on FIGS. 2 and 3, the lugs 36 extend the inneredge of the radial portion 30 a of the target holder. The lugs 36delimits together with the radial portion 30 a the bore of the targetholder. The lugs 36 are disposed around the axial portion 34 a of thesleeve.

In the illustrated example, the target holder 30 comprises a pluralityof lugs 36. The lugs 36 are identical to one another. The lugs 36 arespaced apart from each other in the circumferential direction,preferably regularly. Here, the target holder 30 comprises three lugs36. Alternatively, the number of lugs may be at least equal to two. Inanother variant, the target holder 30 may comprise only one lug 36.

Each lug 36 of the target holder extends axially into a slot 38 formedon the lateral face 16 d of the inner ring. Each slot 38 extends axiallyfrom the lateral face 16 d into the thickness of the inner ring. Eachslot 38 is oriented axially toward the radial portion 30 a of the targetholder. In the illustrated example, each slot 38 opens radially into thegroove 16 e of the bore. Alternatively, each slot 38 may not openradially into the groove 16 e. In this case, a radial wall subsistsbetween the groove 16 e and each slot 38. The slot 38 are identical toone another.

Each slot 38 extends in the circumferential direction over a limitedangular sector. The circumferential dimension of each slot 38 issubstantially equal to the one of the associated lug 36. Each slot 38 isprovided with two lateral walls 38 a, 38 b (FIG. 4) facing each other inthe circumferential direction. The lateral walls 38 a, 38 b delimit theslot in the circumferential direction.

Any relative rotation of the target holder 30 relative to the inner ring16 is prevented by the abutment of each lug 36 with the lateral walls 38a, 38 b of the associated slot 38.

The slots 38 of the inner ring form local anti-rotation meanscooperating by circumferential contact with the lugs 36 of the targetholder which form local complementary anti-rotation means.

The second example shown on FIGS. 5 and 6, in which identical part aregiven identical references, differs from the first example in that thelugs 40 of the target holder 30 extends obliquely towards the inner ring16 of the bearing rather than axially. Only the orientation of the lugs40 differs from the first example.

Each lug 40 of the target holder extends into a slot 42 extending fromthe lateral face 16 d of the inner ring. Each slot 42 extends obliquelyinwards from the lateral face 16 d. In the illustrated example, eachslot 42 opens into the groove 16 e of the bore.

Similarly, to the slots of the inner ring of the first example, eachslot 42 extends in the circumferential direction over a limited angularsector. The circumferential dimension of each slot 42 is substantiallyequal to the one of the associated lug 40. Each slot 42 is provided withtwo lateral walls 42 a, 42 b facing each other in the circumferentialdirection. The lateral walls 42 a, 42 b delimit the slot in thecircumferential direction.

The length of lugs 40 of the target holder 30 may be designed such thattheir free ends protrude into the thickness of the axial portion 34 a ofthe sleeve. This further enhances the anti-rotation between the sleeve34 and the target holder. Alternatively, it could be possible that thelugs 40 of the target holder remains spaced apart from the axial portion34 a of the sleeve. In this case, an annular radial gap subsists betweenthe target holder 30 and the axial portion 34 a of the sleeve.

The third example shown on FIGS. 7 to 9, in which identical part aregiven identical references, differs from the previous examples in thatthe local anti-rotation means of the inner ring 16 cooperate with localanti-rotation means provided on the sleeve 34 of the impulse ring.

In this example, the anti-rotation means of the inner ring 16 comprisesa plurality of axial grooves 44 extending from the lateral face 16 d ofthe inner ring axially along the cylindrical groove 16 e of the bore.Each groove 44 is oriented radially toward the axial portion 34 a of thesleeve. The grooves 44 are spaced apart from each other in thecircumferential direction, preferably regularly.

Each groove 44 extends in the circumferential direction over a limitedangular sector. Each groove 44 is provided with two lateral walls 44 a,44 b facing each other in the circumferential direction. The lateralwalls 44 a, 44 b delimit the groove in the circumferential direction.

The sleeve 34 comprises a plurality of axial bosses 46 each extendingradially into one of the axial grooves 44 and being of complementaryshape. The bosses 46 form the anti-rotation means of the sleeve 34. Thebosses 46 extends outwards from the axial portion 34 a of the sleeve.The bosses 46 extends outwards from the outer surface of the axialportion 34 a. The bosses 46 protrude radially outwards. The bosses 46extend axially along the axial portion 34 a of the sleeve.

Any relative rotation of the sleeve 34 relative to the inner ring 16 isprevented by the abutment in the circumferential direction of each boss46 with the lateral walls 44 a, 44 b of the associated groove.

In the illustrated example, the inner ring 16 and the sleeve 34respectively comprise a plurality of axial grooves 44 and bosses 46.Alternatively, the inner ring 16 and the sleeve may comprise only onegroove 44 and one boss 46.

In the fourth example shown on FIGS. 10 to 12, in which identical partare given identical references, the anti-rotation means of the innerring 16 comprise a plurality of radial grooves 48 formed on the lateralface 16 d of the inner ring. Each groove 48 extends radially on thelateral face 16 d. Each groove 48 is oriented axially toward the radialportion 30 a of the target holder. The grooves 48 are spaced apart fromeach other in the circumferential direction, preferably regularly.

Each groove 48 extends in the circumferential direction over a limitedangular sector. Each groove 48 is provided with two lateral walls 48 a,48 b facing each other in the circumferential direction. The lateralwalls 48 a, 48 b delimit the groove in the circumferential direction.

The target holder 30 comprises a plurality of radial bosses 50 eachextending axially into one of the radial grooves 48 and being ofcomplementary shape. The bosses 50 form the anti-rotation means oftarget holder 30. The bosses 50 extends outwards from the radial portion30 a of the target holder. The bosses 50 protrudes axially. The bosses50 extend radially along the radial portion 30 a of the target holder.

Any relative rotation of the target holder 30 relative to the inner ring16 is prevented by the abutment in the circumferential direction of eachboss 50 with the lateral walls 48 a, 48 b of the associated groove.

In the illustrated example, the inner ring 16 and the target holder 30respective comprise a plurality of axial grooves 48 and bosses 50.Alternatively, the inner ring 16 and the target holder 30 may compriseonly one groove 48 and one boss 50.

In the fifth example shown on FIGS. 13 to 15, in which identical partare given identical references, the inner ring 16 of the bearingcomprises the axial grooves 44 and radial grooves 48 as disclosed in thethird and fourth examples. The sleeve 34 and the target holder 30 alsorespectively comprise the bosses 46, 50.

In the sixth example shown on FIG. 16, in which identical part are givenidentical references, the inner ring 16 of the bearing comprise anannular eccentric groove 52 formed on the lateral face 16 d of the innerring. The center of the eccentric groove 52 is radially offset with therotation axis of the bearing. The eccentric groove 52 is orientedaxially toward the radial portion 30 a of the target holder.

The target holder 30 comprises an annular eccentric rib 54 extendingaxially into the eccentric groove 52 and being of complementary shape.The rib 54 extends outwards from the radial portion 30 a of the targetholder. The rib 54 protrudes axially.

Any relative rotation of the target holder 30 relative to the inner ring16 is prevented by wedging of the eccentric rib 54 into the eccentricgroove 52.

The eccentric groove 52 of the inner ring form annular anti-rotationmeans cooperating by wedging with the eccentric rib 54 of the targetholder which form annular complementary anti-rotation means.

In the illustrated examples, the sensor bearing unit is provided with arolling bearing comprising one row of rolling elements. Alternatively,the rolling bearing may comprise at least two rows of rolling elements.In the illustrated examples, the rolling elements are balls.Alternatively, the rolling bearing may comprise other types of rollingelements, for example rollers. In another variant, the rolling bearingmay also be provided with a sliding bearing having no rolling elements.

Otherwise, as previously mentioned, in these illustrated examples, thefirst ring of the rolling bearing is the inner ring whereas the secondring is the outer ring. As an alternative, it could be possible toprovide a reversed arrangement with the first ring forming the outerring and the second ring forming the inner ring. In this case, thetarget holder is secured to the outer ring.

1. A sensor bearing unit comprising: a bearing having a first ring and asecond ring centered on an axis, and an impulse ring provided with atarget holder, with a target mounted on the target holder, and with asleeve secured to the first ring of the bearing, the target holder beingaxially mounted between a lateral face of the first ring of the bearingand the sleeve, wherein the first ring of the bearing comprisesanti-rotation means cooperating with complementary anti-rotation meansof the impulse ring so as to prevent angular movement of the impulsering relative to the first ring, the anti-rotation means of the firstring of the bearing being formed on the lateral face of the first ringand/or extending from the lateral face, the complementary anti-rotationmeans of the impulse ring extending into the anti-rotation means of thefirst ring or vice versa.
 2. The sensor bearing unit according to claim1, wherein the anti-rotation means of the first ring of the bearing andthe complementary anti-rotation means of the impulse ring extend in thecircumferential direction over a limited angular sector.
 3. The sensorbearing unit according to claim 1, wherein the sleeve comprises amounting portion secured to the first ring of the bearing which extendspurely axially.
 4. The sensor bearing unit according to claim 1, whereina radial gap subsists between the bore of the target holder of theimpulse ring and the sleeve.
 5. The sensor bearing unit according toclaim 1, wherein the anti-rotation means of the first ring of thebearing comprise at least one anti-rotation recessed portion.
 6. Thesensor bearing unit according to claim 5, wherein the anti-rotationrecessed portion comprises at least one slot formed on the lateral faceof the first ring of the bearing, the target holder of the impulse ringcomprising at least one lug extending into the slot, the lug forming atleast partly the complementary anti-rotation means of the impulse ring.7. The sensor bearing unit according to claim 5, wherein theanti-rotation recessed portion comprises at least one axial grooveextending from the lateral face of the first ring of the bearing axiallyalong a cylindrical surface of the first ring, the sleeve comprising atleast one boss extending into the axial groove and being ofcomplementary shape, the boss forming at least partly the complementaryanti-rotation means of the impulse ring.
 8. The sensor bearing unitaccording to claim 5, wherein the anti-rotation recessed portioncomprises at least one radial groove formed on the lateral face of thefirst ring of the bearing, the target holder comprising at least oneboss extending into the radial groove and being of complementary shape,the boss forming at least partly the complementary anti-rotation meansof the impulse ring.
 9. The sensor bearing unit according to claim 5,wherein the anti-rotation recessed portion comprises an eccentric grooveformed on the lateral face of the first ring of the bearing, the targetholder comprising an eccentric rib extending into the eccentric grooveand being of complementary shape, the eccentric rib forming at leastpartly the complementary anti-rotation means of the impulse ring.
 10. Amethod for manufacturing a sensor bearing unit comprising: providing abearing having a first ring and a second ring centered on an axis, andan impulse ring provided with a target holder, with a target mounted onthe target holder, and with a sleeve secured to the first ring of thebearing, the target holder being axially mounted between a lateral faceof the first ring of the bearing and the sleeve, wherein the first ringof the bearing comprises anti-rotation means cooperating withcomplementary anti-rotation means of the impulse ring so as to preventangular movement of the impulse ring relative to the first ring, theanti-rotation means of the first ring of the bearing being formed on thelateral face of the first ring and/or extending from the lateral face,the complementary anti-rotation means of the impulse ring extending intothe anti-rotation means of the first ring or vice versa, and securingthe sleeve to the first ring by axial press-fitting.